/*
 * Copyright (c) 2021, 2021, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.oracle.svm.truffle.api;

import org.graalvm.compiler.truffle.runtime.GraalFastThreadLocal;
import org.graalvm.nativeimage.Platform;
import org.graalvm.nativeimage.Platforms;

import com.oracle.svm.core.SubstrateUtil;
import com.oracle.svm.core.threadlocal.FastThreadLocal;
import com.oracle.svm.core.threadlocal.FastThreadLocalFactory;
import com.oracle.svm.core.threadlocal.FastThreadLocalObject;

final class SubstrateFastThreadLocal extends GraalFastThreadLocal {

    static final SubstrateFastThreadLocal SINGLETON = new SubstrateFastThreadLocal();
    private static final FastThreadLocalObject<Object[]> CONTEXT = FastThreadLocalFactory.createObject(Object[].class, "SubstrateFastThreadLocal.CONTEXT")
                    .setAllowFloatingReads(true)
                    .setMaxOffset(FastThreadLocal.FIRST_CACHE_LINE);

    @Platforms(value = Platform.HOSTED_ONLY.class)//
    private static final ThreadLocal<Object[]> SLOW_CONTEXT_LOCAL = new ThreadLocal<>();

    SubstrateFastThreadLocal() {
    }

    @Override
    public void set(Object[] data) {
        if (SubstrateUtil.HOSTED) {
            SLOW_CONTEXT_LOCAL.set(data);
        } else {
            CONTEXT.set(data);
        }
    }

    @Override
    public Object[] get() {
        if (SubstrateUtil.HOSTED) {
            return SLOW_CONTEXT_LOCAL.get();
        } else {
            return CONTEXT.get();
        }
    }

}
